The present application is based on Japanese Patent Applications No 2001-180916 and No. 2001-180917, which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a tape running apparatus used for recording information on and reproducing information from magnetic tape, such as video cassette tape, and to a motor board of a motor for use in the tape running apparatus.
2. Related Art
As shown in FIG. 5, a tape running apparatus incorporated into a video cassette recorder (VCR) has a drum motor 102 for rotating a cylinder drum 101, which holds a magnetic head (not shown), a loading motor 103 for drawing out video cassette tape to the magnetic tape, and a capstan motor 104 for running video cassette tape at a constant speed. These motors 102, 103, and 104 are mounted on a common chassis 105, and supplied with driving power and drive control signals from a recorder-body-side circuit board 106.
Generally, motor driving ICs 107 and 108 used for driving the capstan motor 104 and the drum motor 102 are mounted on the motor boards 109 and 110, respectively. A motor driving IC 111 for driving the loading motor 103 is mounted on the circuit board 106.
The motor board 109 of the capstan motor 104 opposes to the circuit board 106. Thus, electrical connection is established between this motor board 109 and the circuit board 106 through a pair of inter-board connectors 112. On the other hand, the motor board 110 of the drum motor 102 does not oppose to the circuit board 106. Thus, electrical connection is established therebetween through a full flat cable 113. In this case, full-flat-cable connecting connectors 114 and 115 are mounted on the boards 110 and 116, respectively. Further, in the case of the loading motor 103 to be driven by using the motor drive IC 111 that is mounted on the circuit board 106, electrical connection is established between this loading motor 103 and the circuit board 106 through a lead wire 116 with a connector, which is drawn out of the loading motor 103. In this case, on the circuit board 106, a receiving side connector 117 for connecting the lead wire thereto is mounted. The connector 118 attached to the lead wire 116 is connected and fixed to this receiving side connector,
However, such an ordinary tape running apparatus needs a pair of inter-board connectors 112, two connectors 114 and 115 for a full flat cable, a single full flat cable 113, a single lead wire 116 with a connector, and a single receiving-side connector 117 for connecting the lead wire 116 thereto so as to establish electrical connection between the circuit board and each of the three motors. Thus, such a conventional tape running apparatus has a problem in that the cost for establishing such the electrical connection is high. Moreover, the working voltages of individual motors often differ from one another. Thus, the conventional tape running apparatus has problems in that in such a case, the power cost thereof is expensive, and that the number of devices, such as capacitors, provided around the power supply increases.
To solve such problems, and to reduce the cost and size of the tape running apparatus, in recent years, there has been proposed motor drive ICs each of which is configured by incorporating drive circuits for two motors into a single motor drive IC. For examples, a motor drive IC, into which a motor a drive circuit for a capstan motor and a drive circuit for a loading motor are incorporated, and a motor drive IC, into which a motor a drive circuit for a drum motor and a drive circuit for a loading motor are incorporated, have been proposed.
Further, on a component mounting surface of the motor board, IC lands for soldering lead terminals of a motor drive IC thereonto, and wiring lands for wiring and connecting to external equipment are disposed. Generally, soldering of junction cables which is used for connecting the external equipment thereto to the wiring lands are conducted after the lead terminals of the motor drive IC are soldered to the IC lands.
The wiring cost for establishing electrical connection between the circuit board and each of the motors can be reduced by using such a motor drive IC. Moreover, the number of connectors can be decreased Consequently, such a motor drive IC is considered to be advantageous in downsizing of the tape running apparatus.
However, the amount of heat radiated from the motor drive IC is large, so that countermeasures against heat radiation are necessary. Thus, countermeasures, such as addition of silicone grease and that of a heat sink, are taken. Such countermeasures, however, are unfavorable because of the facts that the cost of the apparatus is increased for those, and that the countermeasures hinder reduction in size of the apparatus.
Further, such a motor drive IC is unfavorable because of the facts that when such a motor drive IC is mounted on the circuit board, the size of the circuit board is increased or the reduction in the size thereof becomes difficult, and that noises due to a switching operation performed in the motor drive IC are superposed on signals in other circuit portions, which are mounted on the circuit board, so that there is fear of adversely affecting picture signals and speech signals.
In view of such circumstances, an object of the invention is to propose a tape running apparatus enabled to establish electrical connection between a circuit board and each of three motors without increasing the cost of the apparatus, and hindering the reduction in size of the apparatus, and being adversely affected by motor noises.
Further, in the case that the wiring lands and the IC lands are disposed on the component mounting surface of the motor board in such a way as to oppose to each other, unnecessary solder may adhere to a part between the IC lands to which the lead terminals of the motor drive IC are soldered when the junction cable is soldered thereto. Thus, a solder bridge put in a state where a short-circuit is established between the IC lands is apt to be generated. Furthermore, there is possibility that a similar solder bridge is formed between the wiring lands and the IC lands.
It is sufficient for preventing solder bridge that the wiring lands are formed at a distance from the IC lands to which the motor drive IC is soldered. However, the motor board is required to have a limited size. In particular, the recent tendency is shifted to reduce the size of the apparatus. Thus, it is sometimes difficult to place the wiring lands at a sufficient distance from the IC lands. Furthermore, if the IC lands and the wiring lands are not properly disposed, there could be caused adverse effects that places for drawing junction cables to connect the external equipment are limited.
However, in the case of the conventional apparatus, no consideration is given to the placement relation between the wiring lands and these IC lands. Therefore, as matters stand, no proper placement of such lands has been proposed.
Accordingly, in order to adapt downsizing of the apparatus, another object of the invention is to provide a motor board, in which wiring lands are disposed at positions where solder bridge could not be formed among IC lands connected to lead terminals of a motor drive IC or between IC lands and wiring lands when externally connected wiring cables are soldered to the wiring lands, and, where the externally connected wiring cables can be properly drawn around.
To solve the aforementioned problems, according to the invention, there is provided a tape running apparatus having a circuit board, a drum motor, a loading motor and a capstan motor, wherein a motor board of the capstan motor opposes to the circuit board. Further, a motor drive IC into which a drive circuit for the capstan motor, a drive circuit for the drum motor and a drive circuit for the loading motor are incorporated is mounted on the motor board. Furthermore the motor board of the capstan relays electrical connections between the circuit board and two of the drum motor and the loading motor.
The Electrical connections may be established by using an inter-board connector for establishing electrical connection between the motor board and the circuit board, and a junction wire for establishing electrical connection between the motor board and each of the drum motor and the loading motor.
In this case, the junction wire may be a junction cable that comprises a circuit-board-side part connected to the circuit board, and branch parts branched from the circuit-board-side part and connected to the drum motor and the loading motor, respectively.
The tape running apparatus of the invention employs the motor drive IC, into which the drive circuits for the three motors are incorporated. Moreover, in this tape running apparatus, the motor drive IC is mounted on the motor board of the capstan motor, which opposes to the circuit board. Therefore, the electrical connections between the circuit board and the three motors can be established by using a pair of inter-board connectors and a junction wire. As compared with the conventional apparatus, the wiring cost of the apparatus can be reduced. Furthermore, the invention is advantageous in downsizing of the tape running apparatus.
Furthermore, because the motor drive IC is mounted on the motor board of the capstan motor, the invention prevents occurrences of adverse effects that motor noises intrude circuit parts mounted on the circuit board and adversely affect picture signals and speech signals.
Further, it is desirable that a metallic board providing good heat dissipation is employed as the motor board in the tape running apparatus of the invention. This eliminates the necessity for applying silicone grease onto and adding a heat sink to the motor drive IC as the countermeasures to radiate heat therefrom.
Furthermore, according to the invention, on a motor board having a board surface, on which IC lands, to which lead terminals of a motor drive IC are soldered, and wiring lands to be connected to externally connected wires are mounted, the wiring lands are placed at positions where the wiring lands do not oppose to the IC lands mounted on the board surface.
Because each of the IC lands does not oppose to the wiring lands, there is no fear that an unnecessary solder bridge is formed between the IC lands or between the wiring lands and the IC lands when externally connected wiring cables are soldered to the wiring lands.
It is desirable that the wiring lands are disposed on the corner part of the surface of the motor board. That is, preferably, in the case that the board surface has a surface region defined by a first side, and second and third sides respectively extended from both ends of this first side in a direction differing from a direction along which the first side extends, the wiring lands are placed on a first corner part, which is defined by the first side and the second side, or on a second corner part, which is defined by the first side and the third side, in this surface region.
Further, in the case that the wiring lands include at least a first wire land portion and a second wire land portion, it is sufficient that the first wire land portion is disposed on one of the first and second corner parts, while the second wire land portion is disposed on the other corner part.
Thus, one of two sides of the corner part can be selected as a direction in which the externally connected wire is drawn, Consequently, the flexibility in designing the layout of wiring to suitably draw the wire therearound is enhanced. Furthermore, when a jig for soldering the wire to the board is manufactured, the two sides of the motor board can be employed as a reference side. This facilitates the manufacturing of the jig.
Furthermore, in the case of using a video reproducing apparatus adapted to drive and control a plurality of motors as the reduction in size and thickness thereof has been achieved, it is preferable that the wiring lands, which are respectively connected to the motors, are placed on the corner parts, as described above, because of the fact that usually, no electronic components are disposed on corner parts of the motor board even when the number of components mounted on the board increases, and thus such parts can be effectively utilized.
Further, the invention relates to the motor board of the capstan motor of the tape running apparatus. On the surface of this motor board, the IC lands, to which lead terminals of the motor drive IC are soldered, and the wiring lands for connecting the externally connected wires thereto are formed. Furthermore, the wiring lands are disposed at positions where the wiring lands do not oppose to the IC lands. Further, the wiring lands include at least the first wire land portion and the second wire land portion. The first wire land portion is disposed on one of the first and second corner parts. The second wire land portion is disposed on the other corner part. Furthermore, the first wire land portion is used for connecting the wire to the drum motor. The second wire land portion is used for connecting the wire to the loading motor.
Furthermore, the invention relates to the capstan motor having the motor board of this configuration, This capstan motor has a motor drive IC mounted on the motor board. In this motor drive IC, a drive circuit for driving the drum motor, and a drive circuit for driving the loading motor are incorporated.